J. Phil Thien's Projects

retired2 has brought us to this fundamental truth which is of course the cornerstone of all dust collection systems:

QuoteI hated all my toil in which I toil under the sun, seeing that I must leave it to the man who will come after me, and who knows whether he will be wise or a fool? Yet he will be master of all for which I toiled and used my wisdom under the sun. This also is vanity. So I turned about and gave my heart up to despair over all the toil of my labors under the sun, because sometimes a person who has toiled with wisdom and knowledge and skill must leave everything to be enjoyed by someone who did not toil for it. This also is vanity and a great evil. What has a man from all the toil and striving of heart with which he toils beneath the sun? For all his days are full of sorrow, and his work is a vexation. Even in the night his heart does not rest. This also is vanity.

...

Behold, what I have seen to be good and fitting is to eat and drink and find enjoyment in all the toil with which one toils under the sun the few days of his life that God has given him, for this is his lot.

Ecclesiastes 2:18-21, 5:18

I've recently fallen deep down the Thien baffle rabbit hole. I appreciate the contributions many of you have made here, especially those such as retired2 who have experimented with different configurations and provided detailed data. Very valuable and helpful. Oh and Phil too. :) I've spent a lot of time thinking and reading about how to set up dust collection for my garage woodshop. I'm currently just using a 5gal Ridgid shop vac which fills up so fast it's usually clogged. I don't even bother connecting it to my planer. I'm eager to have a more robust solution that I don't have to empty as often. I've got parts on the way (including the Harbor Freight 2HP Dust Collector and some 1/16 polycarbonate for a top hat). Yesterday I got a 55gal drum to collect chips, and I've started on the top hat.

So, getting to my question
In all my research, I haven't seen anyone put a secondary stage of filtration above the first stage as I've sketched below. Normally, what I've labeled part B is next to part A, which roughly doubles the footprint. A stacked configuration could fit in the average garage, because (1) the Thien baffle is so much shorter than a cyclone, and (2) the dust bag/bucket for the secondary stage doesn't need much capacity when it's preceded by the first stage.

Is there some reason this is not a good solution? These are the potential drawbacks I speculate about:

• I imagine there would be some loss in efficiency from having to bend 180 degrees up into the secondary stage, rather than shooting straight into it. In my case, I have a small shop and am planning on just connecting to one tool at a time with that quick change handle from Rockler, without doing any long runs of pipe. So depending on the severity, I may be willing to sacrifice some efficiency for saving floor space.
• The whole assembly could get top-heavy if it's intended to be mobile. And the more you kick out the casters to stabilize, the less you're actually saving floor space. In my case, I'm using a metal 55gal drum which would help keep the center of gravity low. And the components of "part B" are not heavy. Plus I may end up mounting to a wall.
• Maybe I'm wrong and the dust bag/bucket for the secondary stage does need to be tall to minimize scrubbing.

Bonus question: I can't find a 1 micron filter bag right now. I'm looking for something like the Powertec part #70001 (I'd post a link if I could) but I can't find it in stock anywhere. Was the COVID-19 pandemic a bad time to nerd out about micron-level air filtration?  ;) That is, are they normally easier to find? I'm not ready to nearly double the cost of this project by getting a Wynn filter at this time. I'm planning to forego the second stage and duct the output from the first stage outside the garage door, at least as a short term solution. Any input on getting a cheap <=1 micron filter would be most welcome!

Thanks for reading!